1. Field of the Invention
The present invention relates to a fixing belt, a fixing apparatus including the fixing belt and an image forming apparatus including the fixing apparatus.
2. Discussion of the Background
An image forming apparatus, for example, a copier, a printer, or a facsimile heretofore includes a photoconductor drum and forms an electrostatic latent image by exposing a photosensitive layer with a laser beam from a laser scanning unit after the photosensitive layer of the photoconductor drum has received an appropriate charge. After developing the electrostatic latent image using a toner, an image is provided on a transfer paper. After the transfer paper passes through a heat fixing device, the image is fixed.
In such a heat fixing device, a fixing roller includes an adhesive layer composed of a fluorine contained resin layer. The adhesive layer prevents the toner from sticking to a circumferential face of a cored bar composed of, for example, aluminum.
The above described fixing roller includes a heater such as a halogen lamp provided along a centerline of the cored bar which is cylindrical. The fixing roller is heated from inside by heat radiation. The heat fixing device includes a pressure roller which presses the fixing roller. Therefore, the heat fixing device melts and entrenches the toner on the transfer paper by moving the transfer paper through a nipped part between the pressure roller and the fixing roller.
Generally, in such a heat fixing device, the roller is coated with a fluorine contained resin, which easily comes off the roller. However, even if using a coated fixing roller, it is possible that the melted toner will adhere to a surface of the fixing roller and a likelihood exists that the transfer paper will wrap around the fixing roller because the melted toner is doughy and has a high-viscosity. Therefore, the heat fixing device includes a part called an exfoliative click for preventing the transfer paper from wrapping around the fixing roller.
However, in the case that the exfoliative click contacts the fixing roller, the exfoliative click may damage the fixing roller and the damage may result in defective images. As a result, the exfoliative click has been designed to reduce damage to the fixing roller. For example, in some devices, the exfoliative click includes a surface layer composed of a fluorine contained resin, which is an adhesive, and, in other devices, the exfoliative click includes a rounded corner. However, the design of the exfoliative click can still result in damage to the fixing roller resulting in paper powder when paper is transferred between the exfoliative click and the fixing roller.
The following described fixing belt is used for fixing layered multi colored toners on transfer paper. The fixing belt includes an elastic layer composed of silicon rubber on a belt composed of a metal or polyimide and an adhesive layer composed of a fluorine contained resin layer for preventing toner adherence. The fixing belt is provided between a heating roller, which is a cylinder including a heat source internally provided, and a fixing roller faces the heating roller. This heat fixing device includes a pressure roller pressing the fixing roller through the fixing belt. Therefore, the heat fixing device moves the transfer paper through a nipped part between the pressure roller and the fixing belt, melts a toner on the transfer paper by heating the fixing belt, and entrenches a toner on the transfer paper by applying pressure.
However, the above fixing belt has a problem that the exfoliative click may puncture and damage the elastic layer when the exfoliative click contacts the fixing belt.
To address this problem, Japanese Laid-Open Patent Application No. 2006-171551 discloses that the heat fixing device includes a separation board having a width greater than a maximum width of a transfer paper provided at a vent of the nipped part between the pressure roller and the fixing belt. Further, there is a gap provided between the separation board and the fixing belt. Therefore, the heat fixing device prevents the transfer paper from winding around the fixing belt because the separation board separates the transfer paper from the fixing belt. Here, guided part mounted on the separation board contacts a surface of the fixing belt forming the gap.